Wet clutch assembly

Abstract

A hydraulically-actuated wet clutch assembly which is responsive to torque or speed and is adapted to be utilized as a starting clutch for a continuously variable transmission or similar item. This clutch connects the continuously varying means to the driving gears when the engine speed is increased from idle rpm. The clutch will engage as the fluid pressure increases from idle rpm through a pressure responsive valve or directly with a piston area defined between a piston and a cylinder, with the cylinder and attached pressure plate being movable under pressure relative to the piston to engage a clutch plate located between the piston and movable pressure plate.

We claim: 
     
       1. A hydraulically-actuated starting clutch comprising a piston operatively connected to a rotating shaft, a movable cylinder encompassing and sealingly engaging said piston to provide a pressure cavity therebetween, a friction plate facing said piston opposite to said cylinder and operatively connected to a driven shaft, a pressure plate secured to said cylinder for movement therewith and positioned on the opposite side of the friction plate from the piston, guide means between said piston and cylinder to cause simultaneous rotation thereof, a source of hydraulic fluid pressure actuated by the speed of the rotating shaft to pressurize said pressure cavity, said rotating shaft having a central passage therethrough for the introduction of the hydraulic fluid, said piston having a feed hole communicating between said shaft passage and the pressure cavity, and a yieldably biased reciprocable control valve received in an enlarged end of said shaft passage and adapted to uncover a side passage communicating with said feed hole at a predetermined pressure level, said control valve having a cylindrical body portion conformably received in said shaft passage, an annular groove in the exterior surface of said body and communicating with longitudinal slots in the rear end, and a reduced diameter nose forming with said passage an annular space adapted to communicate with said piston feed hole. 
     
     
       2. A hydraulically-actuated starting clutch as set forth in claim 1, in which a plug closes the open end of the passage and has a central drain opening, said control valve passage having a central recess opening towards said plug, and a compression spring with one end abutting said plug and the opposite end received in said recess. 
     
     
       3. A hydraulically-actuated starting clutch as set forth in claim 1, in which said guide means comprises a plurality of cylindrical pins secured in said piston and extending through openings in the reciprocable cylinder. 
     
     
       4. A hydraulically-actuated starting clutch as set forth in claim 3, wherein said pins have enlarged heads beyond said cylinder, and retractor springs encompassing said pins with the opposite ends abutting said cylinder and said enlarged heads. 
     
     
       5. A hydraulically-actuated starting clutch as set forth in claim 4, in which said pins are bolts threadingly engaging said piston. 
     
     
       6. A hydraulically-actuated starting clutch as set forth in claim 1, wherein said pressure cavity is located adjacent said rotating shaft and defined between a pair of annular pressure seals positioned on axially extending surfaces of said piston. 
     
     
       7. A hydraulically-actuated starting clutch as set forth in claim 1, in which said driven shaft encompasses and is concentric with said rotating shaft. 
     
     
       8. A hydraulically-actuated starting clutch as set forth in claim 1, in which said pressure cavity is spaced radially outward from the rotating shaft beyond said guide means, said cavity being defined between a pair of annular pressure seals, one of which is positioned on the outer periphery of said piston and the other is positioned on an axially extending surface on the piston beyond the guide means. 
     
     
       9. A hydraulically-actuated starting clutch comprising a piston operatively connected to a rotating shaft, a movable cylinder encompassing and sealingly engaging said piston to provide a pressure cavity therebetween, a friction plate facing said piston opposite to said cylinder and operatively connected to a driven shaft, a pressure plate secured to said cylinder for movement therewith and positioned on the opposite side of the friction plate from the piston, guide means between said piston and cylinder to cause simultaneous rotation thereof, said pressure cavity being spaced radially outwardly from the rotating shaft beyond said guide means, said cavity being defined between a pair of annular pressure seals, one of which is positioned on the outer periphery of said piston and the other is positioned on an axially extending surface on the piston beyond the guide means, said guide means including a plurality of bolts threadingly engaging said piston, a clutch cover having openings receiving said bolts adjacent the enlarged heads thereof and an axially extending flange with an annular pressure seal engaging said cylinder, and a retractor spring encompassing each said bolt with the opposite ends abutting the cylinder and the clutch cover, and a source of hydraulic fluid pressure actuated by the speed of the rotating shaft to pressurize said pressure cavity. 
     
     
       10. A hydraulically-actuated starting clutch as set forth in claim 9, wherein said pressure cavity is in direct communication with the source of hydraulic pressure and said retractor springs are preloaded so as to overcome the hydraulic pressure generated at idle rpm and provide a running clearance for the clutch. 
     
     
       11. A hydraulically-actuated starting clutch comprising a piston operatively connected to a rotating shaft, a movable cylinder encompassing and sealingly engaging said piston to provide a pressure cavity therebetween, a friction plate facing said piston opposite to said cylinder and operatively connected to a driven shaft, a pressure plate secured to said cylinder for movement therewith and positioned on the opposite side of the friction plate from the piston, guide means between said piston and cylinder to cause simultaneous rotation thereof comprising a plurality of bolts threadingly engaging the piston adjacent its periphery and extending through said cylinder, a clutch cover having openings receiving said bolts, a retractor spring encompassing each bolt with the opposite ends thereof abutting the cylinder and clutch cover, said cover having an offset providing a secondary pressure cavity, and a free floating annular piston in said last-mentioned cavity and having a pressure seal engaging said cover, and a source of hydraulic fluid pressure actuated by the speed of the rotating shaft to pressurize said pressure cavity. 
     
     
       12. A hydraulically-actuated starting clutch as set forth in claim 11, in which said secondary pressure cavity and free-floating piston act to balance the first-mentioned pressure cavity by being equal to the centrifugal head thereof to prevent an increase in plate load when the clutch is rotated. 
     
     
       13. A hydraulically-actuated starting clutch as set forth in claim 11, including a spacer sleeve encompassing each bolt and extending through said cylinder with the opposite ends thereof abutting the piston and clutch cover, said retractor springs encompassing said sleeves. 
     
     
       14. A hydraulically-actuated starting clutch as set forth in claim 11, in which said first-mentioned pressure cavity is in direct communication with the source of hydraulic pressure and said retractor springs are sufficiently preloaded to overcome the pressure at idle rpm and maintain a running clearance in the clutch. 
     
     
       15. A hydraulically-actuated starting clutch as set forth in claim 14, in which said rotating shaft has a central passage communicating with the source of hydraulic pressure, and said cylinder is closed by an end plate to define the pressure cavity. 
     
     
       16. A hydraulically-actuated starting clutch as set forth in claim 11, including at least one feed opening in the cylinder to allow fluid to exit from the said first-mentioned pressure cavity to said secondary pressure cavity. 
     
     
       17. A hydraulically-actuated starting clutch as set forth in claim 11, including a nut threadingly engaging said rotating shaft and having a central opening communicating with the source of hydraulic pressure and a side opening communicating with said first-mentioned pressure cavity. 
     
     
       18. A hydraulically-actuated starting clutch as set forth in claim 17, in which said cylinder has an axially extending inner flange in sliding engagement with said last-mentioned nut, and a pressure seal between the cylinder flange and nut. 
     
     
       19. A hydraulically-actuated starting clutch as set forth in claim 18, including a non-rotating spout sealingly received in the central opening in said nut, said spout communicating with the source of hydraulic pressure. 
     
     
       20. A hydraulically-actuated starting clutch as set forth in claim 11, including an end plate closing the inner periphery of said cylinder, and a rotating union connected to said end plate and to a flexible hose communicating with said source of hydraulic pressure.